For millennia, man has used woven textile goods for a variety of domestic and industrial applications. To enable woven materials to be put to use, techniques were developed to reinforce the edges such that the textile could be attached to a secondary structure to do work. As an example, seafarers from antiquity developed the durable techniques of sewing attachment straps and using grommets on those reinforced edges that allowed cloth panels to be affixed to a secondary structure such as a mast and connected to a pole or control rope to drive a vessel through the water by the force of wind. Two principle factors limited the ability of a sail to transfer the potential wind energy into a force to drive a vessel: the first being the strength of the cloth; the second being the method used to reinforce the edge and affix the sailcloth to the support structure. While today these traditional techniques are widespread, it was over much of the course of known history that these methods were developed.
The range of applications for industrial textiles prior to the development of modern synthetic materials was self limiting. Natural fibers could be made no stronger than their natural state. The techniques based on principles of sewing hems to reinforce the edge and attaching grommets or straps to fasten the textiles made from these fibers were largely sufficient, as the strength of these methods of reinforcement and attachment often exceeded the strength of the fibers in the textile itself. The only way to make a stronger textile panel was to increase the quantity of fibers in the textile. Textiles of natural fibers quickly became impractical for many high load applications which naturally limited the development of additional uses and methods of attachment. The rise of modern synthetic fibers yielded textiles that are far stronger than textiles of natural fibers and have resulted in a vast number of new and innovative products.
Current art describes a range of textile devices intended for load applications which use some form of the traditional methods to reinforce and attach the edges. U.S. Pat. No. 6,176,050 issued to Gower and U.S. Pat. No. 6,959,748 issued to Hudoba show examples of textiles used as a hurricane barriers. Gower uses straps sewn onto a hemmed and stitched edge, while Hudoba uses grommets on an edge reinforced by welding a second strip of material. Similar to Gower, U.S. Pat. No. 4,781,473 issued to LaFleur shows straps for lifting sewn onto a large flexible material bulk container whose edges have been reinforced with layered and stitched hems. Similar to Hudoba, U.S. Pat. No. 5,529,321 issued to Thompson shows a hauling harness for a load carrying tarp which has double layer reinforced edges with grommets. U.S. Pat. No. 7,216,908 issued to Daigle, shows a textile lift bag used to load and unload bulk materials more easily; its edges are hemmed and reinforced with sewn on webbing to which lift straps are sewn. U.S. Pat. No. 4,290,243 issued to Mellin discloses a method of attaching a fabric used in tension structures; this system reinforces the edge of the textile with a hemmed in cable, which is then used as an attachment point for the secondary structure.
The applications listed above demonstrate uses for textiles using traditional methods to secure the reinforced the edge of the textile and attach it to a secondary structure. While these current methods of sewn or welded hems to reinforce edges using straps or grommets to transfer loads are generally successful in moderate load applications, they do not perform as well as possible. Point loading tends focus the load to a limited number of fibers within the panel around the points of attachment such as grommets or straps. This places a greater strain on the fibers directly in line with the grommet or strap making these fibers vulnerable to failure. Additionally, distortion occurs along the border edges as the few fibers aligned with the anchor points bear the greatest percentage of the load. Compounding failures occur across the reinforced edge as the highly tensioned fibers break, causing shock loads to the remaining fibers which cause them to break as well.
Another family of current art uses better load distribution along the edge of the load bearing textile. U.S. Pat. No. 5,915,449 issued to Schwartz describes a textile blast screen which uses a hemmed in rod to reinforce the top and a hemmed in lead weight to reinforce the bottom; these also serve as attachment points. U.S. Pat. No. 5,746,343 issued to Waltke et al shows a textile bag for liquids supported by having its edges sewn onto a frame. Similarly, U.S. Pat. No. 5,329,719 issued to Holyoak shows a textile containment method for raising and harvesting fish in a body of water having edges that are also sewn onto a frame. While these products have less likelihood of failure at the attachment point and less likelihood of distortion because the loads are better distributed across the panel, the sewn hem is still a potential point of failure. When structural elements are comprised of stitched materials, the panel is subject to stress failure due to shear loading of the stitch. Further still, the process of stitching fabric inherently weakens the textile. Damage to the thread itself, whether by abrasive action or ultraviolet degradation is a concern to manufacturers and consumers of load bearing textile devices. The difficulty is in identifying the progressive degradation and establishing a time period and protocol by which the effective service life of the device can be determined. Additionally, current art disclosures that rely on traditional methods of manufacture are not able to take advantage of labor saving manufactured components and are therefore required to have skilled labor, large facilities and complex machinery to produce a reliable and consistent product. Ultimately these disadvantages increase consumer costs and make the products less desirable. Additionally still, no part of a sewn seam or grommet assembly can be reused nor is it easily repaired in the field.
Current art shows that industry has recognized these problems and has set forth a range of textile clamps and attachment methods which attempt to address the issues above. U.S. Pat. No. 4,686,748 issued to Kaivanto, U.S. Pat. No. 5,692,272 issued to Woods, and U.S. Pat. No. 5,168,605 issued to Bartlett each show a clip for holding fabric. While these clips are all improvements over sewn methods, they still describe single points of attachment that are subject to the same point loading concerns previously noted. In order to distribute loads evenly across the terminating edge, an excess of these textile clamps would be required. U.S. Pat. No. 2,266,466 issued to Linder sought to remedy the issue of point loading and the requirement for skilled labor to assemble chair seats. Linder describes a continuous strip of material worked in such a way to form a clamping jaw, where the jaw interacts with a rod and fabric to form a textile clamp. In use the clamping jaw is first held closed by a series of rivets then the clamp is secured to a chair frame with a fastener. One drawback of Linder is the requirement of punching multiple holes to secure the strip to the textile making it a labor intensive operation requiring specialized tools and not practical for use in the field. Another drawback is the inability to mass manufacture a functional item in a single piece.
Limited to methods described in prior art for securing a textile panel to a secondary structure, industry is not able to take full advantage of the strength of modern fibers in high load applications. What is needed is a method to further increase the load carrying capacity of an article made of high strength synthetic fibers which may be applied/affixed/deployed without the need for specialized skill, facilities or tools.